Empty/Gross weight Vs. Max. Pilot weight

In article ,
(Flyhighdave) wrote:

Hi All!
I'm confused by the weight restrictions on most gliders.
As an example the Lak-12 specs show the following:

Empty weight: 794lbs.
Gross weight: 1433lbs.
Payload: 693lbs.
Max. Water 416lbs.
Max. Pilot: 242lbs.(110KG)

Why is the pilot weight restricted to a max. of 242lbs? It seems to
me like the difference between the empty & gross weights could be
made up of any combination of pilot, equipment & ballast as long as
the gross weight is not exceeded & the C.G. remains within limits.
What am I not understanding here?

- max weight of non-lifting parts (think: strength of the fuselage
mountings)

- seat and seatbelt mounting point strength

- C of G out of limits, possibly meaning not enough up elevator
available at low speeds (e.g. landing round-out)


As any of you know who have read my numerous recent questions to this
group I am a new and BIG pilot trying to figure out which ships will
work for me & learn a little more about this endeavor. I could weigh
as much as 250lbs fully equipped in the winter. That appears to
exceed the limits of almost all gliders.

The day I'm 242 lbs, including parachute, will be a minor miracle.
Right now I'm 260. Several months ago, around the beginning of spring,
I was over 270. Several years ago when I was dotcommed for a while and
bicycled 30 - 50 km every day during a Chicago summer I got down to
about 250 briefly.

I've flown quite a few gliders, at quite a few places in NZ and the USA,
and no one has *ever* suggested that I shouldn't be flying their gliders
due to weight. Sometimes I've had a conversation with an engineer or
instructor and we've agreed that I'll mentally knock 5 or 10 knots off
the placarded rough air/manouvering speeds and keep the G loading down.
I do that anyway. It's probably not necessary.

Just because it's easy to do, here's a logbook dump of the types I've
flown. Not a lot of experience, I know, but more than zero...

Glider Type Flights Total PIC Avg
=============== ======= ====== ====== ===
Club Libelle 36 56:55 56:55 95
Blanik 110 46:56 27:38 26
Janus 43 36:55 30:02 52
Ka6CR 21 26:26 26:26 76
PW-5 19 20:04 20:04 63
Twin Astir 27 14:42 12:08 33
Std Libelle 9 9:32 9:32 64
Grob 103 3 3:13 3:13 64
ASK21 6 2:42 2:42 27
Ka7 16 1:52 0:14 7
ASK13 3 1:32 1:15 31
Duo Discus 1 1:07 0:00 67
Puchacz 1 1:02 0:00 62
T53 1 0:37 0:00 37
Phoebus C 1 0:33 0:33 33
Pirat 1 0:19 0:19 19

I haven't had problems with any of the above types, although I'm
probably over the placarded weight for all of them (and some, such as
the K6 and the Std Libelle are a bit of a squeeze).

People flying marginal powered aircraft are, rightly, quite a bit more
concerned about weights. Put full tanks and two big people in a Cessna
152 and it probably won't climb at *all*.

-- Bruce